The AU announced the reinstatement late Wednesday as it called for a plan to restore state authority in northern Mali, which is under the control of Islamists, Radio France Internationale reported Thursday.
The AU called for Mali to hold elections early next year.
The AU action comes as a food crisis is growing in northern regions of the country, Peter Maurer, president of the International Committee of the Red Cross, said. He said help is needed for people fleeing the Islamist-held areas for the south or neighboring countries.
French Defense Minister Jean-Yves Le Drian said Wednesday preparation for deployment of AU troops was in its early stages, pulling back from his suggestion last week that intervention in Mali was imminent.
France has promised to support any AU force with training, logistics and equipment.